Die tool, device and method for producing a lens wafer

ABSTRACT

This invention relates to a die tool, a device and a method for producing, in particular embossing, a monolithic lens wafer that has a large number of microlenses.

FIELD OF THE INVENTION

This invention relates to a die tool, a device and a method forproducing, in particular embossing, a monolithic lens wafer that has alarge number of microlenses.

BACKGROUND OF THE INVENTION

Microlenses are primarily used for devices that require an opticalfocusing system, such as, for example, for cameras of mobile telephones.Because of the push for miniaturization, functional areas are to besmaller and smaller. The more the microlenses are to be miniaturized,the more difficult will be their optically correct production, since atthe same time, there is an enormous cost pressure for the microlensesthat are ideally to be produced in mass production. In the prior art,microlenses are produced on a carrier substrate by different productionmethods, as shown in, for example, U.S. Pat. No. 6,846,137 B1, U.S. Pat.No. 5,324,623, U.S. Pat. No. 5,853,960 and U.S. Pat. No. 5,871,888. Itis a common aspect of all previously-mentioned methods that, based onprinciple, a certain thickness is necessary and the light that goesthrough the microlens has to pass through not only the lens but thecarrier substrate. Because of the simultaneously called-for high qualityand the requirements for higher resolution with simultaneously higherbrilliance, which depends on, i.e., the thickness and the number ofoptics along the optical axis, i.e., the beam path, another optimizationof the microlenses according to the prior art is desirable.

Moreover, the requirement exists for as high a light yield as possible,which is decisive in particular for microoptics systems since, in mostcases, the image sensor occupies a very small surface on which light canoccur.

A production method for an unsupported microlens field is disclosed inEP 2 168 746 A1.

In the production of unsupported microlens fields, the shrinkage of thelens field material is problematic during the production of the lensfield, in particular during embossing and curing.

SUMMARY OF THE INVENTION

The object of this invention is to indicate a die tool or a genericdevice or a generic method with which, in particular in mass production,lens wafers can be produced with microlenses of high light yield as wellas high brilliance and simultaneously higher production accuracy.

This object is achieved with the features of the independent claims(s).Advantageous further developments of the invention are indicated in thesubclaims. All combinations that consist of at least two of the featuresindicated in the description, the claims and/or the figures also fallwithin the scope of the invention. In the case of the indicated valueranges, values as boundary values that are within the above-mentionedlimits are also to be regarded as disclosed and can be claimed in anycombination.

The invention is based on the idea of configuring a die tool for theproduction of the lens wafer in such a way that the die is designedbordering an embossing space for holding the curable fluid for theproduction of the lens field in such a way that during embossing orproduction of the lens field, a lateral peripheral edge of the lensfield is automatically designed. In this way, the further processing ofthe lens field is clearly simplified, since already present carriersystems and handling devices can be used for this purpose. At the sametime, it is made possible to produce a very homogeneous, optimallycuring lens field with higher accuracy. By the configuration accordingto the invention, in addition it is possible to produce virtually anylens shapes with a single embossing step as a monolithic lens wafer witha large number of microlenses, in particular spherical and/oraspherical, convex and/or concave, as well as Fresnel lenses.

According to the invention, because of the configuration of the dietool, an unsupported microlens field can be produced in whichmicrolenses have a smaller thickness than microlenses with carriersbecause the carrier is eliminated.

According to an advantageous embodiment of the die tool, it is providedaccording to the invention that the projection is designed as aparticularly annular, preferably circular, bank, in particular with aninside diameter Di of 200 mm, 300 mm or 450 mm. In this respect, thehandling of the lens wafer is further simplified.

In addition, it is advantageously provided that during embossing, theembossing space is partially bordered, in particular above, by thesecond embossing side.

According to another advantageous embodiment of the invention, it isprovided that at least one of the dies, in particular the first die, ispermeable to electromagnetic radiation. In this way, not only the curingby irradiation through the die can take place, but also the detection ofsome orientation marks for orientation and wedge error compensation inthe production of the lens wafer.

The invention is further developed in that the first die has firstorientation marks for orienting the first die relative to the secondorientation marks of the second die. In this respect and in particularby integration of the orientation marks in the die, preferably in theprojection, a high-precision orientation of the die is made possible,and because of the configuration, according to the invention, of the dietool with a projection, subsequent errors in the further processing andfurther handling are minimized or completely eliminated. From the edgeof the lens wafer produced with the die tool according to the invention,the position of any individual microlens that is provided in the lenswafer can be determined precisely, even if shrinkage of the lens wafermaterial has taken place.

With this invention, orientation accuracy in the X- and Y-directions ispossible with a reproducible accuracy of less than 3 μm, in particularless than 1 μm, preferably less than 0.5 μm, and still more preferablyless than 0.1 μm, of deviation in orientation accuracy.

In addition to the previously described die tool, the device accordingto the invention has the following features:

-   -   A first holding system for, in particular statically fixed,        holding of the first die on a holding side that faces away from        the first embossing side. The holding system can be a chuck,        which is mounted on a fixed or static frame. The fixing of the        first die can be done, for example, by vacuum grooves.    -   A second holding system for holding the second die on its        holding side that faces away from the second carrier side. The        holding system can be designed in particular also as a chuck,        preferably with a fixing by vacuum grooves.

The device is designed in such a way that it can embody a controlledmovement of the second die in an X-Y plane and a Z-direction that runsorthogonally thereto as well as a controlled rotation around an axis ofrotation that runs parallel to the Z-direction for orienting the firstdie to the second die. The X-Y plane is essentially parallel to theembossing sides of the die during embossing.

In addition, the device can be controlled so that the orientation isdone based on the position of the die, in particular the position of theorientation marks.

According to an advantageous embodiment of the device according to theinvention, a lift drive is provided, by which the movement of the secondholding system can be executed in the Z-direction. The lift driveconsists in particular of three motorized spindle drives positionedparallel to one another in axial direction and independent of oneanother, preferably rotationally symmetrical on the periphery at anangular distance of 120 degrees. In this respect, on the one hand, theparallel movement of the second die with the holding system in theZ-direction is made possible. On the other hand, the lift drive cansimultaneously cause the second drive to tip over.

If the device according to the invention comprises wedge errorcompensating means, with which a wedge error between the dies can becompensated for, the dies can be oriented exactly parallel to oneanother, by which a homogeneous lens with an optimal optical axis can beproduced. This is particularly important when several lenses are laterstacked.

The wedge error compensating means are advantageously provided as anorienting table or chuck, which is fixed to the lift drive.

In another embodiment of the invention, it is provided that optics,movable in particular in the Z-direction, are provided for detecting theposition of each of the orientation marks in the X-, Y- andZ-directions.

The method according to the invention is characterized with the use ofthe previously described die tool and/or the previously described deviceby the following method steps:

-   -   The dies are arranged and fixed relative to the corresponding        holding systems,    -   If necessary, an at least rough orientation (so-called        pre-alignment) of the dies to one another in the X- and        Y-directions as well as in the direction of rotation is carried        out around the axis of rotation, in particular with an accuracy        of less than 100 μm, preferably less than 50 μm, and still more        preferably less than 10 μm,    -   A wedge error compensation is done by wedge error compensating        means to orient the embossing sides in parallel, in particular        with an accuracy of less than 5 μm, preferably less than 3 μm,        and still more preferably less than 1 μm,    -   Then, the application of a curable fluid, in particular a        polymer, is carried out in fluid form on one of the flat        embossing sides, in particular the second embossing side, which        preferably is arranged below and—because of the projection—forms        an embossing space, whose bottom forms the second embossing        side,    -   Embossing the lens wafer by shaping and subsequent curing of the        curable fluid, whereby shaping is done by moving the dies onto        one another.

According to an advantageous embodiment of the method, it is providedthat the embossing is done without contact between the dies. In thisway, an open ring gap is formed on the side edge of the embossing space,where said ring gap is designed allowing a lateral exit of the curablefluid when shaping or embossing the lens wafer.

If the embossing is done based on force and/or position in theZ-direction, a precise definition and homogenous production of the lenswafer is possible with a reproducible accuracy of less than 10 μm, inparticular less than 5 μm, preferably less than 3 μm, and still morepreferably less than 1 μm, of deviation in orientation accuracy.

The first and second dies are configured as lens dies with the negativesthat form the microlenses, i.e., concave/convex embossing structures,whereby spherical/aspherical and/or Fresnel lenses are also conceivable.At a diameter of a lens die of approximately 200 mm, for example,approximately 2,000 microlenses can be embossed in one embossing step.

The curable fluid can be formed, according to the invention, from aUV-settable or thermosettable material, whereby the lens materialaccording to the invention is at least predominantly—preferablycompletely—solvent-free and is suitable for complete cross-linking.

Because of the monolithic production of the lens wafer according to theinvention, the latter has a homogeneously thermal expansion coefficient,so that any microlens produced from the lens wafer is self-similar undervarying temperature conditions and almost does not change its opticalproperties.

Other advantages, features and details of the invention will emerge fromthe subsequent description of preferred embodiments and based on thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Shows a diagrammatic, cut side view of a device according to theinvention for the production of a lens wafer that has a large number ofmicrolenses,

FIG. 2a : Shows a diagrammatic, cut side view of a die tool according tothe invention for the production of a lens wafer that has a large numberof microlenses in a first embodiment,

FIG. 2b : Shows a diagrammatic, cut side view of the die tool accordingto the invention in a second embodiment,

FIG. 2c : Shows a diagrammatic, cut side view of the lens wafer that isproduced with a die tool according to FIG. 2a or FIG. 2b or a deviceaccording to FIG. 1,

FIGS. 3a to 3c : Show a diagrammatic representation of the course of theprocess of the embossing of a lens wafer with the die tool according toFIG. 2 a,

FIGS. 4a to 4c : Show a diagrammatic representation of the course of theprocess of the embossing of a lens wafer with the die tool according toFIG. 2 b,

FIGS. 5a to 5c : Show a diagrammatic, cut side view of the die toolaccording to the invention in a third embodiment and the correspondingcourse of the process of embossing of the lens wafer, and

FIG. 6: Shows a diagrammatic top view of a second die of the die toolaccording to FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

In the figures, advantages and features of the invention arecharacterized with these identifying reference numbers in each caseaccording to the embodiments of the invention, whereby components orfeatures with the functions that are the same or that act the same arecharacterized with identical reference numbers.

In FIG. 1, a system that consists of a device according to the inventionwith a die tool according to the invention is shown. The die toolconsists of a first die 1 and a second die 2, and the die tool is shownin detail in a first and second embodiment according to FIGS. 2a and 2band further described below. In FIG. 1, the die tool is used in thedevice according to the embodiment shown in FIG. 2 a.

The first die 1 is fixed on its first holding side 23, in particularhorizontally, by at least one vacuum strip 25 on a first holding system21. The first holding system 21 is fixed rigidly and as vibration-freeas possible by a particularly annular, preferably circular, holdingdevice 27, in particular to a massive frame that is not shown in thefigures.

The first holding system 21 is designed as a chuck that is at leastpartially permeable, in particular for electromagnetic radiation. Theelectromagnetic radiation is in particular visible or UV light. Thefirst die 1 is also permeable to electromagnetic radiation, inparticular visible light.

The first die 1 has in particular embedded first orientation marks 4 a,4 i, in particular on its first embossing side 6 opposite to the firstholding side 23. The position of the first orientation marks 4 a, 4 i ina horizontal X-direction in FIG. 1 and in a Y-direction that isorthogonal to the X-direction as well as in a Z-direction that runsperpendicular thereto can be detected by—in particular—an opticaldetector system that consists here of microscopes 32, 33,

The detector system, in particular the microscopes 32, 33, can be movedin the X-, Y- and/or Z-directions and in each case can be fixed to beable to detect the positions of the orientation marks 4 a, 4 i. Thedetector system operates in such a way that it sends out electromagneticradiation in the direction of the orientation marks 4 a, 4 i and thusdetects the position of the orientation marks 4 a, 4 i. The detectorsystem is arranged on the side of the first holding system 21 that facesaway from the first holding side 23, i.e., above the first die 1 and thefirst holding system 21, and it is mounted on the frame.

A second holding system 22 is arranged below the first holding system 21and the first die 1 and can be oriented relative to the first holdingsystem in the X-, Y- and/or Z-directions. In addition, the secondholding system 22 can be rotated by a rotational system 28 around anaxis of rotation that runs in the Z-direction. The movement in theX-direction is embodied by an X drive 29, which is controlled by acontrol system, not shown. The movement in the Y-direction is embodiedby a Y drive 30 that also is controlled by the control system and thatis arranged adjacent to the X drive 29. Moreover, the control systemcontrols the rotational system 28 and the method of the detector systemor the individual microscopes 32, 33.

The movement of the second holding system 22 in the Z-direction iscarried out by a lift drive 31, in particular consisting of actors 34,35, 36. The actors 34, 35, 36 are oriented to act in particular in theZ-direction. As actors 34, 35, 36, for example, spindles are suitable.The actors 34, 35, 36 can be controlled in each case individually by thecontrol system. The actors 34, 35, 36 are arranged distributedpreferably on a side periphery below the X drive 29, the Y drive 30 orthe rotational system 28, so that the components arranged on the liftdrive 31 rest securely on the lift drive, and a precisely controllablemovement of the second holding system 22, in particular a wedge errorcompensation, can be carried out by the in- and out-movement of theactors 34, 35, 36 that can be controlled independently of one another.

The second die 2 can be held in the second holding system 22 on a secondholding side 24 that is opposite to the first holding side 23. Thefixing is done by at least one vacuum strip 26, which preferably isarranged on the side periphery of the second die 2.

The second die 2 has in particular a second orientation mark 5 a, 5 i,in particular embedded, on its second embossing side 7 that faces awayto the first holding side 23. The positions of the second orientationmarks 5 a, 5 i can be detected by the detector system arranged above thefirst holding system 21, so that a precise control of the movement ofthe first die 1 relative to the second die 2 is made possible by thedetection of the positions of the corresponding orientation marks 4 a, 4i, 5 a, 5 i that are arranged opposite in each case.

The first embossing side 6 can thus be arranged and oriented paralleland opposite to the second embossing side 7, namely during the entireembossing process.

The first embossing side 6 has first embossing structures 8, and thesecond embossing side 7 has second embossing structures 9. The embossingstructures 8, 9 correspond to the negative of a top side 11 and a bottomside 12 of a lens wafer 10 produced with the die tool or the deviceaccording to the invention; each corresponding opposite individualstructure of the first and second embossing structures 8, 9 thuscorresponds to the negative of a first optically active surface 13 and asecond optically active surface 14 of the corresponding microlens 20.The microlenses 20 can be separated after the production of the lenswafer 10, for example by cutting.

Outside of the surface formed by the embossing structures 8, 9, aparticularly annular, preferably circular, projection is providedaccording to the invention at least on one of the two dies 1, 2, inparticular at least on the second die 2. The projection is designed inparticular as a bank 3, 3′.

In the embodiment of the invention shown in FIG. 2a , only the seconddie 2 has a bank 3 that projects from the second embossing side 7 andrises above the second embossing structures 9. With its wall 3 wpointing in the direction of the second embossing structures 9, theprojection together with the second embossing side 7 forms a tublikespace that is part of an embossing space 19.

In addition, the embossing space 19 is formed in the embossing positionaccording to FIGS. 3c and 4c of the first embossing side 6.

On its particularly circular wall 3 w, the embossing space 19 has aninside diameter Di that essentially corresponds to the diameter of thelens wafer 10 to be produced according to FIG. 2b . In this case, thisessentially means that a possible shrinkage of the lens wafer 10 is tobe taken into consideration during embossing or curing.

In the embodiment shown in FIG. 2b , the first die 1 also has aprojection that is designed as a bank 3′, which borders the embossingspace 19 with a wall 3 w′ corresponding to the wall 3 w.

In the embodiment of the invention shown in FIG. 2a , at least twoinside orientation marks 4 i arranged in the area of the first embossingstructures 8 are provided as first orientation marks 4 a, 4 i. Inaddition, at least two outside orientation marks 4 a are providedoutside of the first embossing structures 8, in particular outside ofthe projection.

In the embodiment of the invention shown in FIG. 2b , the outsideorientation marks 4 a are provided in the projection, in particular inthe bank 3. The bank 3 is arranged opposite the bank 3′ and is designedcorresponding to the latter.

The bank 3, 3′ has an annular width B and a height H, whereby the heightH or—in the embodiment according to FIG. 2b —the heights H1, H2 of thebanks 3, 3′ correspond approximately to the heights of the first andsecond embossing structures 8, 9.

By the integration of the outside orientation marks 4 a, 5 a in the bank3, 3′, not only the position of the orientation marks 4 a, 5 a, but atthe same time also the position of the banks 3, 3′ can be detected inthe Z-direction, whereas the height H is stored in the embodimentaccording to FIG. 2 a.

By the device according to the invention, the dies 1, 2 can becontrolled so that in the embossing position, at least between a face 37of the bank 3 and a face 38 of the first embossing side 6 that can bearranged opposite or the bank 3′, a distance R is provided, which isless than or equal to the height H, H1 or H2 of the bank 3 or the banks3, 3′.

In FIGS. 3a and 4a , the dies 1, 2 are separated so far that a curablefluid 15 is applied, in particular as a wet spot, to the secondembossing side 7. The wet spot is produced because of the surfacetension of the curable fluid 15. The curable fluid 15 is preferablyapplied centered, thus almost equidistant or concentrically to the wall3 w.

According to FIGS. 3b and 4b , the second die 2 is moved to the firstdie 1 by the lift drive 31 in the Z-direction so that the curable fluid15 that is still present in fluid form gradually penetrates in thedirection of the wall 3 w until the embossing position shown in FIGS. 3cand 4c is reached.

The amount of curable fluid 15 is metered exactly so that the embossingspace 19 in the embossing position is almost completely filled by thecurable fluid 15. The amount is advantageously measured so that a roundperipheral edge is produced on the lateral upper peripheral edge 18 ofthe lens wafer 10, so that the orientation of the lens wafer 10 can beeasily determined. The lens wafer 10, conditioned by production, has asquare edge on the opposite lateral peripheral edge.

During the movement of the dies 1, 2 toward one another, controlled bythe control system, the positions of the orientation marks 4 a, 4 i, 5a, 5 i are continuously detected by the detector system and forwarded tothe control system, which forwards the necessary control commands forthe rotational system 28 to the X drive 29, the Y drive 30, and the liftdrive 31, or the individual actors 34, 35 and 36 from the relativepositions of the corresponding orientation marks 4 a, 4 i, 5 a, 5 i. Awedge error compensation can simultaneously be carried out by the actors34, 35 and 36.

Since a minimum distance R between the first die 1 and the second die 2is provided in the embossing position, a homogeneous and perfect shapeof the lens wafer 10 can be ensured, whereby also a shrinkage of thecurable fluid during embossing or curing to form the finished lens wafercan be taken into consideration.

The lens wafer 10 that is produced by the device according to theinvention or the method according to the invention or the die toolaccording to the invention can be handled directly and without furtherprocessing steps after the embossing because of its specified outsidecontour by standardized wafer processing tools.

A further special advantage of the invention consists in that amonolithic lens wafer 10 can be produced according to the invention, inwhich a carrier substrate can be eliminated so that the shape factor ofwafer level cameras produced from such lens wafers 10 or the microlenses20 obtained therefrom can be reduced, and simultaneously decreases theproduction costs, since mass production is easily possible.

The use of a polymer as a curable fluid has a further positive effect onthe costs of the microlenses 20.

The shrinkage of the curable fluid during embossing or curing can thusbe optimized so that the lift drive 31 is based on force.

For the further processing of the monolithic lens wafer, the followingproperties of the lens wafer can be taken into considerationsimultaneously by the die tool and the device according to theinvention, namely the outside diameter, the thickness and the automaticembossing of the alignment passmarks in the lens wafer 10 for latermachining processes, for example the cutting of the lens wafer 10 toseparate the individual microlenses 20.

The actors 34, 35, 36 are designed in particular as three motorizedspindles that are positioned parallel to one another and are operatedindependently of one another, in particular by rotational symmetry at aninterval of 120°. In this respect, the parallel movement of theorienting table that consists of the X drive 29 and the Y drive 30 andthe rotational system 28 is made possible together with the tool holdingdevice, i.e., the second holding system 22 in the Z-direction as well assimultaneously the tilting in any direction, which is necessary for thewedge error compensation. The wedge error compensating means accordingto the invention can be seen herein.

During the embossing process, the embossing force can be continuouslymeasured and simultaneously adjusted by pressure-measuring cellsintegrated into the lift drive 31, in particular into each actor 34, 35,36. The pressure-measuring cells can be implemented, for example,between the spindles and the point of support on the bottom of theorienting table. According to an alternative embodiment of theinvention, the first holding system 21 is not static, but can be drivenin at least one prescribed direction, i.e., the X-, Y- and/orZ-directions and/or in the direction of rotation.

The orientation of the dies 1, 2 can also be carried out before thecurable fluid 15 is applied to the second die 2.

The curing of the curable fluid 15 is done in particular by UV radiationand/or thermal curing.

Relative to the orientation of the dies 1, 2 (alignment), the method ofthe microlens embossing according to the invention is assigned to thethick layer processes. Because of the thickness of the monolithic lenswafer 10 of between 0.2 mm and 2 mm and the limited depth of focus rangeof the optical detector system, the detector system is positioned in theZ-direction so that the orientation marks 4 a, 4 i, 5 a, 5 i of the dies1, 2 can be imaged exactly during the orienting process within the depthof focus of the detector system. As an alternative to this, it isconceivable according to the invention that the detector system isstatically fixed in the Z-direction, and a synchronous method of the diein the Z-direction is carried out.

In this respect, the embodiment according to FIG. 2b is especiallyadvantageous, since the orientation marks 4 a and 5 a are at thesmallest possible distance from one another.

According to a preferred embodiment of the invention, the exactorientation of the die is carried out in the X- and Y-directions as wellas in the direction of rotation with a reproducible accuracy of lessthan 3 μm, in particular less than 1 μm, preferably less than 0.5 μm,and more preferably less than 0.1 μm, of deviation only during thecontinuous embossing process, in particular against the end of theembossing process, preferably when the final distance R of the embossingposition is essentially reached or when the lens wafer 10 is shaped, butstill not cured.

In another embodiment of the invention, the control of the movement ofthe dies toward one another is taken away, i.e., in particular viameasuring devices for detecting the distance R, which is measuredcontinuously at least at one position on the periphery of the die tool.

To achieve a homogeneous surface of the lens wafer 10, at least themoving-onto-one another up to the embossing position in a vacuum iscarried out according to a preferred embodiment, so that the forming ofgas bubbles or hollow spaces is avoided when filling the embossing space19 by the curable fluid 15.

According to an advantageous embodiment of the invention, it is providedthat a gas-transparent polymer is used as a curable fluid 15.

According to another advantageous embodiment of the invention, it isprovided that at least one of the dies 1, 2 is made from a material withopen porosity, whereby the porosity is measured in such a way that thecurable fluid 15 cannot penetrate into the pores, but gas molecules canescape unimpeded through the porous die.

The ejection process subsequent to the embossing process and curingprocess and in which the lens wafer 10 is ejected is carried out byapplying an overpressure to the side of the porous die opposite to thelens wafer 10.

In the embodiment shown in FIGS. 5a to 5c , in addition to theembodiment shown in FIG. 2b , at least one projection that is designedas a platform 39—in the embodiment shown here, a large number ofplatforms 39—is provided. The height of the platform 39 is at least halfas high, in particular at least ¾, and at most equally as high as theheight H, H1 or H2 of the bank 3. The width of the bank 39 is at leasthalf as wide, in particular at least ¾, and at most equally as wide asthe width B of the bank 3.

The platforms 39 are always equidistant in each case to two adjacentsecond embossing structures 9 of the second die 2 (see FIG. 6).

The platforms 39 are preferably monolithic with the second die 2.

The platforms 39 can project, tapering in particular conically, from theembossing side of the second die 2.

It is especially advantageous to embed the inside orientation marks 5 iin the platform 39, in particular on its side that faces away from thesecond holding system 22. In this way, the distance between thecorresponding orientation marks 4 i is minimized, so that a more precisedetection is made possible by the detector system and all the moreprecise orientation of the dies 1, 2.

The platforms 39 are conceivable in the two embodiments according toFIGS. 2a and 2 b.

In addition, it is provided in one embodiment according to the inventionthat the bank 3 and/or the bank 3′ is/are designed in an elasticallydeformable manner in such a way that during embossing by contact of thefaces 37 and 38, a sealing of the embossing space 19 is carried out.

The first die 1 could be made of, for example, glass, while the seconddie 2 is made of polymer, whereby the polymer of the bank 3 and/or thebank 3′ can consist of softer polymer than the polymer of the second die2.

In FIG. 6, a top view of the second die 2 is shown, and there a secondprojection 40 that points from the bank 3 and/or bank 3′ inward in thedirection of the embossing space 19 is provided, which is responsiblefor the design of a recess on the lens wafer 10. This recess preferablycorresponds to a recess (notch) that is known in the case of wafers. Asa result, the further handling of the lens wafer 10 is clearlysimplified.

To the extent that the orientation marks 4 a, 5 a are designedintegrated in the bank 3 and/or 3′, the banks 3, 3′ perform not only thefunction of the bordering of the embossing space 19, but also provide animproved orientation accuracy since the orientation marks are bunched upcloser together and can be detected more exactly in the detector system.

This also applies for the orientation marks 4 i, 5 i, if the latter aredesigned integrated in the platforms 39.

REFERENCE SYMBOL LIST

-   -   1 First die    -   2 Second die    -   3, 3′ Bank    -   3 w, 3 w′ Wall    -   4 a, 4 i First orientation marks    -   5 a, 5 i Second orientation marks    -   6 First embossing side    -   7 Second embossing side    -   8 First embossing structures    -   9 Second embossing structures    -   10 Lens wafer    -   11 Top    -   12 Bottom    -   13 First optically active surface    -   14 Second optically active surface    -   15 Curable fluid    -   18 Edge    -   19 Embossing space    -   20 Microlens    -   21 First holding system    -   22 Second holding system    -   23 First holding side    -   24 Second holding side    -   25 Vacuum strip    -   26 Vacuum strip    -   27 Holding device    -   28 Rotational system    -   29 X Drive    -   30 Y Drive    -   31 Lift drive    -   32 Microscope    -   33 Microscope    -   34 Actor    -   35 Actor    -   36 Actor    -   37 Face    -   38 Face    -   39 Platform    -   40 Projection    -   Di Inside diameter    -   H, H1, H2 Height    -   B Annular width    -   R Distance

Having described the invention, the following is claimed:
 1. A methodfor the production of a monolithic lens wafer having a large number ofmicrolenses, said method including the following steps, with thefollowing sequence: oppositely arranging and fixing first and seconddies to respective first and second holding systems, the first andsecond dies having first and second embossing sides, respectively; atleast roughly orienting the first and second dies to one another in theX- and Y-directions and around an axis of rotation; applying a curablefluid on one of the first and second embossing sides of said first andsecond dies, respectively; and embossing the lens wafer by shaping andsubsequent curing of the curable fluid, the shaping comprising movingthe second die toward the first die via wedge error compensation meanswithout contacting the first die during the embossing; wherein a wedgeerror compensation for parallel orientation of the first and secondembossing sides is performed using said wedge error compensation meansduring said moving of the second die and/or during the embossing.
 2. Themethod according to claim 1, wherein the embossing is carried out basedon force and/or position.
 3. A method for the production of a monolithiclens wafer having a large number of microlenses, said method includingthe following steps, with the following sequence: oppositely arrangingand fixing first and second dies to respective first and second holdingsystems, the first and second dies having first and second embossingsides, respectively, at least one of the first and second embossingsides having a projection that projects therefrom, the projection atleast partially bordering an embossing space circumferentially; at leastroughly orienting the first and second dies to one another in the X- andY-directions and around an axis of rotation; applying a curable fluid onone of the first and second embossing sides of said first and seconddies, respectively; performing a wedge error compensation using wedgeerror compensating means for parallel orientation of the first andsecond embossing sides; and embossing the lens wafer in the embossingspace by shaping and subsequent curing of the curable fluid, the shapingcomprising moving the first and second dies to an embossing position atwhich, throughout the embossing, a projecting face of the projectionopposes a face of one of the embossing sides from a distance.
 4. Themethod according to claim 3, wherein the projection is comprised of abank.
 5. The method according to claim 3, wherein the first die has aplurality of first embossing structures that corresponds to a negativeof a top side of a lens wafer, wherein at least two inside orientationmarks are arranged in an area of the first embossing structures, andwherein at least two outside orientation marks are provided outside ofthe area of the first embossing structures.
 6. The method according toclaim 3, wherein at least two outside orientation marks are provided inthe projection.
 7. A method for the production of a monolithic lenswafer having a large number of microlenses, said method including thefollowing steps, with the following sequence: oppositely arranging andfixing first and second dies to respective first and second holdingsystems, the first and second dies having first and second embossingsides, respectively, the first and second embossing sides respectivelyhaving first and second projections that respectively project therefrom,the first and second projections at least partially bordering respectiveembossing spaces of the first and second embossing sidescircumferentially; at least roughly orienting the first and second diesto one another in the X- and Y-directions and around an axis ofrotation; applying a curable fluid on one of the first and secondembossing sides of said first and second dies, respectively; performinga wedge error compensation using wedge error compensating means forparallel orientation of the first and second embossing sides; andembossing the lens wafer in the embossing spaces by shaping andsubsequent curing of the curable fluid, the shaping comprising movingthe first and second dies to an embossing position at which, throughoutthe embossing, respective projecting faces of the first and secondprojections oppose each other from a distance.
 8. The method accordingto claim 1, wherein said wedge fault equalization means is comprised ofa plurality of individually movable actuators configured to move thesecond die toward the first die and orient the first and secondembossing sides parallel to each other during the moving of the seconddie and/or during the embossing.